How to Fix Crumbling Plaster Walls

plaster repair is one of those home improvement projects that can be somewhat intimidating. The bigger concern might be finding out why your plaster is crumbling, but that is an issue for another time. Right now, we’re going over how to repair a plaster wall and you may be surprised at how simple this task can be! So here we go, the steps you want to follow to fix your crumbing plaster:

Clear Away the Damage

You need to prep the area that you plan to repair. That means knocking off the loose and chipped plaster that currently exists. Take a chisel and a hammer to remove any flaked and damaged debris that is still hanging and crumbling. Just be careful that you don’t get too overzealous with knocking the loose stuff off, you could end up denting or splintering the wood that exists behind it.

Outline the Damaged Area

If you have a large hole that needs to be fixed in your drywall plaster, you’ll want to work on just this one area, so take a piece of chalk or pencil and draw a rectangular outline around the affected portion. Once you’re done, you might want to screw in some plaster washers beyond the perimeter. Next, take your hammer and chisel and knock out the damaged plaster that is contained within the rectangular outline that you’ve created. Just do it gently so as not to loosen or damage any of the plaster outside of the affected area.

Plaster Mixing

After you’ve done all of your preparations, mix your plaster as per the manufacturer’s instructions. But one thing to keep in mind is ensure that it has the proper consistency. If it’s too thin or too thick you won’t be able to work very effectively with it.


You’ll need a wallboard knife to spread the plaster mix over the damage. You might want to use some drywall tape to fill in larger areas. Start with laying down the first layer of plaster or you can use joint compound instead. After that apply the tape. Repeat the process until the surface area is even. Apply additional layers in a cross-scratched fashion. This is the step that many amateurs will fail to accomplish because they’re not aware of the necessity for it. They will just slather one layer on top of the other without any thought for the cross-scratching.

Applying A Joint Compound

The same as you did with the plaster, mix the joint compound as per your manufacturer’s directions. When it’s ready to go, place the joint compound over the second layer after it has dried fully. Apply with your wallboard knife and smooth it out until the surface is flat and even. Blend this layer of joint compound and then let it dry.

Sanding and Painting

Finally, you want to get a proper grit sandpaper and start sanding the area that you just repaired. Make sure it’s nice and smooth before you prime the area and then paint. Do this slowly so you don’t make any mistakes.